THE Wheel & Tire Thread

[Frank818]

Just thought about something.

I am onto FWD cars, so in the event I take a curve to the limit, if the rear end starts to slide I just counter-steer a little and give it a little gas to trsf weight to the back. Since the power goes to front wheels and they are in the direction I want to go, that technique works perfectly to give grip back to the back.

What would you do with an MR?

If you are at the limit and the rear slides, if you lift off weight will trsf to front, making the rear slide even more.
If you give it gas, it will probably make the rear wheels spin, making the rear end slide more.

So what's the technique here?

[Wayne Presley]

On a street car you would not set up the suspension to have the rear slide in the first place. It would have a push and when the car reached it's cornering limits the front would slide first causing an increase in its turn radius. You get out of the throttle and the weight shifts to the front tires allowing the turn radius to decrease.

[Frank818]

Makes sense. I guess that's what those Koni guys did.

[philly15]

ok so i traded a guy a while a go for some 17x9 RPF1's, +35 offset i believe. does anyone have a set of 17x8's and wanna trade 2 wheels? if so get a hold of me i wouldnt mind swapping and running a staggered setup.

[Wayne Presley]

What bolt circle are the 17x9's?
I can get the RPF1's 17x8's for $960/set plus shipping if anyone wants to split philly's set

[philly15]

5x100

[Xusia]

What color and what condition?

[philly15]

Silver and fairly new I traded a guy in Texas for my 17x8's a while back. He needed 8's for STX and I wanted the 9's for SM. I never ended up running them though I think he only ran em for a couple thousand miles

[Grintch]

5x100

According to the Enkei website, they don't make a 17x9 RFP1 in a 5x100, only in 5x114.

For a different direction, what is the smallest diameter wheel that will fit over the stock WRX 02-06, and 07-08 brakes? Rumour has it that 15" is popular with people rally crossing the earlier cars, and using a dedicated set of small diameter wheels & tires for the track would result in less weight, shorter gearing, and a lower ride height that can very quickly be undone for the ride to/from the track.

[Wayne Presley]

According to the Enkei website, they don't make a 17x9 RFP1 in a 5x100, only in 5x114.

And that is exactly why I asked and the price above was for brand new Enkei wheels as I am a dealer for them.

[philly15]

And that is exactly why I asked and the price above was for brand new Enkei wheels as I am a dealer for them.

they were special order on nasioc for a while in those group buys. thats where the guy got em in 5x100, now if you order from tire rack and go under the BRZ, they have a 17x9 in 5x100...

[Zodiac]

I was searching around and couldn't really find what I was looking for. So what are the recommended tire and wheel sizes? I found a few posts saying 17's front 18's back. 40 offset here and 48 offset there. 215/245. I'm just curious as to what's the recommended so if I find a good deal I can go ahead and get them instead of worrying if it's the right choice. I really do like the Raijin model and trying to go for that as well.

[Wayne Presley]

I'm running a 17x8 with 40 offset in front and 18x9.5 with 40 offset in back. To run that wide of a back rim I had to come up with trailing arms, spacers and lateral links. I will be selling that kit as soon as I do the final prove out on the pieces. What size tires do you want to run? You could do a 16/17, 17/17, 17/18 or 18/18. The Raijins are only available in 18's so let me know when you are ready to order.

[Samiam1017]

Wayne I pm ya awhile back on wheels. Can I get I idea on the cost of the kit too when you get around to it.

[Wayne Presley]

Wayne I pm ya awhile back on wheels. Can I get I idea on the cost of the kit too when you get around to it.

PM sent

[longislandwrx]

I'm running a 17x8 with 40 offset in front and 18x9.5 with 40 offset in back. To run that wide of a back rim I had to come up with trailing arms, spacers and lateral links. I will be selling that kit as soon as I do the final prove out on the pieces. What size tires do you want to run? You could do a 16/17, 17/17, 17/18 or 18/18. The Raijins are only available in 18's so let me know when you are ready to order.

How tight is everything? I originally thought you said a +45 wheel Were those custom? Or are you running a 5mm spacer?

[Wayne Presley]

How tight is everything? I originally thought you said a +45 wheel Were those custom?

I have the suspension done but have not put it on the ground, fitted the body and aligned it yet so I do not know. The wheels on my car are 40, FFR had other offset wheels on their prototype cars. At least 4 sets that I know of.

[longislandwrx]

Awesome. I'm glad it will be possible. 18x9.5 +40 has been my plan from the beginning. BRZ fitment offers tons of choices on new wheels. Lots of companies are selling staggered setups without needing to special order sets. perfect.

Cant wait to see exactly what its going to take.

[Frank818]

As long as you stay in 5x100.
There are that many choices of 18x9.5 +40 in 5x100?

[Twinspool]

Just thought about something.

I am onto FWD cars, so in the event I take a curve to the limit, if the rear end starts to slide I just counter-steer a little and give it a little gas to trsf weight to the back. Since the power goes to front wheels and they are in the direction I want to go, that technique works perfectly to give grip back to the back.

What would you do with an MR?

If you are at the limit and the rear slides, if you lift off weight will trsf to front, making the rear slide even more.
If you give it gas, it will probably make the rear wheels spin, making the rear end slide more.

So what's the technique here?

Drive a 911 and then a Corvette on a twisty track, the answer is somewhere in between those.

[Zodiac]

I was thinking 18x8 for the 5x100 pattern with 245/35 for the back. I found a great deal on the rims but i think those tires are too wide and i dont see the 5x100 offered in 18x9.5 without almost doubling the price of the rims. so I think I have to get 18x8 with something more like 205 or 215 . I've only seen them offered in 45 and 35 offset. I want to basically get them installed without having to get any extra stuff as I'm already going a little over budget as it is. Is that a good match? And I'm assuming it's best to have the front wheels a little smaller than the rear so any ideas on what size I should be looking at for the fronts?

[C.Plavan]

911 example. Just train your foot and brain to ignore each other..... click HD if your connection and computer can handle it.

[longislandwrx]

As long as you stay in 5x100.
There are that many choices of 18x9.5 +40 in 5x100?

yes. go to any online wheel store and look for brz/frs wheels.

[Frank818]

I was thinking 18x8 for the 5x100 pattern with 245/35 for the back. I found a great deal on the rims but i think those tires are too wide and i dont see the 5x100 offered in 18x9.5 without almost doubling the price of the rims. so I think I have to get 18x8 with something more like 205 or 215 .

Well I see 2 tires in that size on Tirerack.com and taking one I see that the recommended rim width is 8-9.5. So 18x8 with 245/35 should be ok.

[Zodiac]

Well I see 2 tires in that size on Tirerack.com and taking one I see that the recommended rim width is 8-9.5. So 18x8 with 245/35 should be ok.

oh really? cool yea i was under the impression it would be too big for the rim. if that's the case I may still be going with that setup. now to chose a size for the front cause don't i need smaller ones?

[Mechie3]

I ran a 255 starspec on a 17x8 once. It fit, but you could feel the sidewall flex during initial turn in which killed my confidence.

[Frank818]

oh really? cool yea i was under the impression it would be too big for the rim. if that's the case I may still be going with that setup. now to chose a size for the front cause don't i need smaller ones?

Yup, but only 2 choices on TireRack, so if it's a rare spec you may have to live with the available tires.

Oh wait!! No, a bunch more than 2!! Sorry my search was bad, but take a look for yourself:

http://www.tirerack.com/tires/TireSe...35&diameter=18

[Zodiac]

Yup, but only 2 choices on TireRack, so if it's a rare spec you may have to live with the available tires.

Oh wait!! No, a bunch more than 2!! Sorry my search was bad, but take a look for yourself:

http://www.tirerack.com/tires/TireSe...35&diameter=18

Cool thanks. Yea been searching around and tirerack and discounttire seem to usually be the best. onlinetires.com has some good deals as well ($153 for hankook v12 evo) as well as on raijin rims. Just gotta check reviews first before i go through them since I haven't heard from them. Bridgestone would be ideal but the price jumps up quit a bit lol

[Grintch]

yes. go to any online wheel store and look for brz/frs wheels.

Yes, but our hardware is Impreza based. The BRZ seems to tend to a slightly lower offset, and allow a little wider fitment.

Typical GD Imprezza offset is 42 - 53mm, and a 9.5" wheel with appropriate size tires would require fender mods. Has anyone got the body & suspension complete enough to get a real feel for the size and configuration of the 818 fender wells? Seen a specific wheel & tire size recommendation from FFR?

As a reminder for track use, NASA TT/ST rules give a pretty good weight/point break to cars running a 245mm size tire or less. And a reduced one to cars running a 275mm tire or less.

[C.Plavan]

Yes, but our hardware is Impreza based. The BRZ seems to tend to a slightly lower offset, and allow a little wider fitment.

Typical GD Imprezza offset is 42 - 53mm, and a 9.5" wheel with appropriate size tires would require fender mods. Has anyone got the body & suspension complete enough to get a real feel for the size and configuration of the 818 fender wells? Seen a specific wheel & tire size recommendation from FFR?

As a reminder for track use, NASA TT/ST rules give a pretty good weight/point break to cars running a 245mm size tire or less. And a reduced one to cars running a 275mm tire or less.

Thanks for the info on the NASA rules. Do we even know where the 818R will fit yet in NASA?

[Grintch]

The FFR Cobra & Daytona are allowed in TT1 - TT3 (time trial) & ST1 - ST3 (racing) with a slight weight penalty, which sub class depends on the power to weight you are at. I expect the 818 will get classed there as well once a few pave the road.

So don't drive too fast, you guys that are first getting your car done, or the rule makers will stick us in higher classes (STR) or stick us with a bigger weight penalty.

[C.Plavan]

The FFR Cobra & Daytona are allowed in TT1 - TT3 (time trial) & ST1 - ST3 (racing) with a slight weight penalty, which sub class depends on the power to weight you are at. I expect the 818 will get classed there as well once a few pave the road.

So don't drive too fast, you guys that are first getting your car done, or the rule makers will stick us in higher classes (STR) or stick us with a bigger weight penalty.

I only know how to drive FLAT OUT.....lol

Good ideas..... I like to sandbag.

[JeromeS13]

I only know how to drive FLAT OUT.....lol

Do you need to be moved to the fastest run group?

[EricScottZehnder]

I just ran through this thread and it seems that most people will go with 30mm split front to rear. What I've also heard people talk about is getting to the upper limit of wheel diameter with a small sidewall. What I'm wondering is why.

As far as I know, you want a small wheel, not massive sidewall, and not overly massive overall tire diameter. Wheels weigh a lot more than rubber. Also, the taller the wheel the smaller the contact patch. I was reading an article recently talking about how people that go from, say, 16" wheels with 215mm rubber to 18" wheels and 235mm rubber are actually getting less grip because the taller tire means smaller overall contact patch. Note: These aren't the exact sizes, just an example.

Would it not be advisable to go for something like 14-16" lightweight wheels with the widest rubber that the car can accommodate and warm up?

Example: Check this F1 car's wheel size vs. rubber.

[C.Plavan]

I just ran through this thread and it seems that most people will go with 30mm split front to rear. What I've also heard people talk about is getting to the upper limit of wheel diameter with a small sidewall. What I'm wondering is why.

As far as I know, you want a small wheel, not massive sidewall, and not overly massive overall tire diameter. Wheels weigh a lot more than rubber. Also, the taller the wheel the smaller the contact patch. I was reading an article recently talking about how people that go from, say, 16" wheels with 215mm rubber to 18" wheels and 235mm rubber are actually getting less grip because the taller tire means smaller overall contact patch. Note: These aren't the exact sizes, just an example.

Would it not be advisable to go for something like 14-16" lightweight wheels with the widest rubber that the car can accommodate and warm up?

Example: Check this F1 car's wheel size vs. rubber.

A taller tire with same width will always have a bigger contact patch. Hypothetically, picture a tall 32inch off road tire, then picture a regular 16" car tire- both the same width. Which one will have a larger contact patch? The off road tire because of it's physical size/diameter. So regardless of the wheel size, the taller the tire, the bigger the contact patch. (Width being constant)

[Xusia]

Also, a smaller sidewall reduces tire flex under cornering. I don't personally think there will really be too much difference for those intending to use it mostly on the street, but it is a concern for some.

[Bob_n_Cincy]

Putting on my engineering hat I look at a racing car that has no tire size restrictions.
Sébastien Loeb decimated all at pikes peak this year running 31/71-18 Michelin Tires.
I believe that translate to a 315mm wide 710mm (28") tall 18" tire.
So there for (28 - 18) /2 = 5" tall sidewalls.
If I scale down the diameters by 10% I get a 25" tire on 16" rims with 4.5" sidewalls.
The Toyo Proxes R888 245/45ZR16 with 8" wide rims are close to the numbers for the rears.
I'm running autocross now 225/45ZR16 all the way around. I will use these on the fronts of the 818

What to you think of my idea?
Bob

tire.jpg

[wallace18]

Putting on my engineering hat I look at a racing car that has no tire size restrictions.
Sébastien Loeb decimated all at pikes peak this year running 31/71-18 Michelin Tires.
I believe that translate to a 315mm wide 710mm (28") tall 18" tire.
So there for (28 - 18) /2 = 5" tall sidewalls.
If I scale down the diameters by 10% I get a 25" tire on 16" rims with 4.5" sidewalls.
The Toyo Proxes R888 245/45ZR16 with 8" wide rims are close to the numbers for the rears.
I'm running autocross now 225/45ZR16 all the way around. I will use these on the fronts of the 818

What to you think of my idea?
Bob

tire.jpg

Bob it is going to hit the frame. See the did you notice The how little thread in the suspension area. Jim the engineer tells how 25" will hit. I think you need 1/2 to 3/4" less dia. JMO.

[Bob_n_Cincy]

Bob it is going to hit the frame. See the did you notice The how little thread in the suspension area. Jim the engineer tells how 25" will hit. I think you need 1/2 to 3/4" less dia. JMO.

My clearance seems to be fine. I'm within 3/8" of the ball joint. I am running stock rims with 55 offset, so my turning center is closer to the middle of the tire.
I'm going to mount all my autocross tires tonight and do a rough alignment.
I'll double check clearance.
Bob

[EricScottZehnder]

A taller tire with same width will always have a bigger contact patch. Hypothetically, picture a tall 32inch off road tire, then picture a regular 16" car tire- both the same width. Which one will have a larger contact patch? The off road tire because of it's physical size/diameter. So regardless of the wheel size, the taller the tire, the bigger the contact patch. (Width being constant)

I found a good calculator here: http://bndtechsource.ucoz.com/index/...alculator/0-20

It looks like this theory holds true but the difference is minimal. What makes a much bigger difference is overall width. Certainly, you're going to want to fill up your wheel wells (within reason) but if the trade is between a tire that is overall taller or overall wider, you're going to want wider. More than any of that, though, is making sure your rubber is of the best compound and set to a tire pressure that, along with the size and construction of the sidewall, gives you good grip and feedback.

Also, non-slick tires have varying tread patterns. Some have large gaps between contact patches which is bad for overall contact patch but good for allowing them to heat up and cool down when necessary.

No wonder games have a hard time simulating this stuff.